Radio receiving apparatus



Nov. 11, 1930. s ocu 1,781,414

RADIO RECEIVING APPARATUS Filed March 22, 1924 Patented Nov. 11, 1930FATE NT 1 OFFICE LLOYD Q. SLOGUMB, 0F FERGUSON, MISSOURI RADIORECEIVINGAPPARATUS Application filed March 22 1924. Serial No. 700,986.

This invention relates to radio receiving apparatus, and with regard tocertain more specific features, to apparatus for amateur use. t

Among the several objects of the invention may be noted the provision ofan accurate and simplified control for wave length, and volume; and theprovision of a simple and inexpensive device for reducing the distortionof sound in a multi-stage audio amplifier. Other objects will be in partobvious and in part pointed out hereinafter.

The invention accordingly comprises the features of construction,combinations of elements, and arrangements of parts, which areexemplified in the constructions hereinafter described and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings, in which is illustrated one of variouspossible embodiments of this invention,

Fig. 1 is a circuit diagram illustrating applicants invention;

Fig. 2 is a vertical; transverse section through the instrument panel,showing a preferred mounting for the variable condenser; and

Fig. 3 is a face view of a coil.

Similar reference characters indicate corresponding parts throughout theseveral views of the drawings.

Referring now more particularly to Fig. 1, there is illustratedapreferred form of Wiring.

This diagram is shown adapted for four tubes 1, 3, 5, 7; an aerial 9; aground 11; an A-battery A; battery (1 1 The tubes are preferably of thetype ordinarily used for amplification, and known as 20l-A.

There are two sets 13,15 ofrelatively movable coils. Each set comprisesa fixed. pri mary, a fixed secondary or grid coil; and a movablesecondary or plate coil.

The set 13 of relatively movable coils comprises a primary 17 of 20turns of No. 22 double-cotton-covered wire, provided with taps 19 (Fig.3) at turns 1 to 13 inclusive a B- Battery B; and a third andat 16 and20 turns. This primary 'coil 17 is connected to ground at 11, and theaerial 9may be connected to the desired tap.

19 (Fig. 3). The plate coil2l of this-set 13 has 70 to 80 turns of No.30 double-cottoncovered Wire wound on the inside of a fibre spider webframe 23 (Fig. 3); the primary winding 17 is wound on the outside ofsaid spider web 23 and is thus close-coupled to the grid coil 25. Themovable or plate coil 21 of the set 13 is of 70 to 80 turns of No.30.double-cotton-covered wire and is on a separate spider web 27 (Fig.2). This spider web 27 is pivotally mounted as at 28 so as to berotatable in a counterclockwise direction (Fig. 2) away from the fixedcoils 17, 25 of the set 13. Such movement of the movable coil 31 securedto the upper end of the movable spider 27 and connected at its other endto glge frame plate 33 of thevariable condenser This condenser comprisesfixed plates 37 and movable plates 39, and is mounted to slide as awhole, in guides 41 secured to the instrument panel 43 by suitablemeans, such as screws 45 (Fig. 2).

Rotation of the knob 47 the movable plates 39 fixed plates 37, therebyof the condenser.

Longitudinal movement of the knob 47,

causes rotation of with respect to the varying the capacity throughoutthe range of travel permitted by the slot 49 in the panel 43, causes thecondenser to move bodily (vertically in Fig. 2). This bodily movementdoesnot affect the internal capacity of the condenser as an instrument,but is primarily for the purpose of varying the relative position of thecoils 17--25 and 21.

A tension spring 51 (Fig. 2) tends to hold the spider 27 toward thespider 23. This spring also serves, if necessary, to counterbalance theeffect of gravity tending to shift the condenser in a direction to pullthe two spiders apart.

The grid coil 25 of the set 13 is connected to the grid of the tube 3.The plate coil 21 of this set 13 is connected to the plate of the tube3.

21 is effected through a cord I tive positionlngand mode denser75 of.0045 mf.: capacity. No condensers are providedat the transformer 69..

hereinafter.

. formers and is connected tothe grid of the detector tube 1, through agrid resistance 59 and. condenser-61 shunted around said resistan'ce.- Avariable condenser 63 is shunted around the grid coil 57.

The construction and relative positioning and mode ofqadjustments of thefixed on1 53,..fixed grid coil 57, movable or plate coil 55, andvariable condenser 63, of the set isthe same asthe construction and.rela

or adj ustments, of the analogous parts in the set 13, to-vvit, thecoils 17,121, and variable condenser respectively.

7 There are three closed-core transformers 6'5, 67,. 69. Eachtransformer comprises two respectively. Each Windwindings P and?) ing'oftrans formers 65 and 67 is bridged by a condenser. The Winding P oftransdenser 71 of .002 mf. capacity,- The coil ofv transformer 65" isbridged by a conofS. turns to P turns is respectively 1,41/ to1 and 3to 1. V

Inthe transformer 69 the S'vvinding; is' bridged by a variableresistance, 77. The

l denser-73 of .0001 capacity.- The coil 3 of transformer 67 is'bridgedby acon- In the transformers 65, 67 and 69 the ratio 6 /2 t0 resistanceelement may c onveniently comprisea graphite line made by an ordinarylead pencil provided With'a movablecontact riding along the length ofthe-line, and the fixed contact at one end of the line. 1 i v Twoair-core transformers 7 9, 81 are utilized. Ai-r core transformer7 9 hastWo W'lIlCl ings 83, 85, each of 20 turns of No. 30 doublecotton-coveredWire. .The' coil 83 is in series Withthe P coil of transformer 67, andthe other coil.85'is in series With the S coil of transformer 67.-

' 7 I Alr-co-re transformer 81 has two windings 87 89, each of turns ofNo. 30 double-cotton-covered wire. Coil 87isin series with thefirst coil53 of the-set 15: The other coil 89 isin series vviththe' P coil oftransformer 69,

- and isconnected to the plate of the tube 5.

A condenser 91 of .0005 mf. capacity is bridged across coil- 87 oftransformer 81. The Air-battery A has a'potential of 6 volts.

5 The B -battery B has a potential of 22 volts.

nected-to ground 1 and 67 is bridged by a con- The third battery C has apotential of 60 to 150 volts. V c

A head set'or other translating device T is connected to the :positiveside of battery C and to the plate of tube 7. v

The filament of each tube is a connected across the A-battery ltheostats93 may be utilized to carry the intensity of the cur-'1 rent inthejseveral filaments.

The negative side of A-battery A is con- From the positive si curtentends through the l? COll of transformer 65, brldged byits condenser71, thence through thepl ate coil 55' of set 15 and thence I I to theplate of tube 1. I v v Fromlthe' negative side of battery B a circuitl'ead's'through the grid coil 57' of set. 15,

- shunted by its. variable condenser 63, thence through the gridresistance 59 shunted by its condenser 61, and thence to the grid oftube 1.;

de of battery B a cir- From the negativesideofbattery A a circuit leadsthrough the S coil of, transform er 65, bridged by its condenser 73thence through the grid coil 25 of set 13, bridged by variable condenser35, and'thence to the grid of tube 3.

From the pos tive side of battery 0 a circuit leads to 'the P coil oftransformer 67,

bridged its condenser71, thence through 5 a the coil 83 of transformer79, thence through the plate coil 21 of? set13, and thence t'o the plateof tube 3. l

' Ajcircuit leads from the negative side of battery A through theS coilof transformer c 67, bridged. byjits condenser 7 5, thence; through thecoil 85 of transformer 79, thence to the grid of tube 5. j, A circuitleads from 69, thence th'r'oughthe' coil 89 of transformer 81, andthence to the plate cftube 5.

A circuit leads from thenegative side of battery A through the S coil oftransformer 69, bridged by its variable resistance 77, thence-to thegrid oftube 7.

the positive side of battery C through the P coiloftr'ans'former Acircuit leads from the positive side of battery C throughthe'tra-nslating device T and thence to'the plate of tube 7. The coil 87of transformer 71 is by the condenser 91 and is connectedto the coil5370f set 15-.v

The operation'of the described circuit is asfollovvs:

Incoming. signals are impressed on thecoil 25 from the aerial 9' Wayoffthe coil 17.

The plate "coilQl functions as a reactance'coil;

Hence the tube 3may be put into-a sensitive conditioncvvith regardto thereactan'ce coil and the reacta'nce coilbuilds up the signal. It may beused to resonate the. circui V t The radio frequency 'signa loutput' ofthe plate of tube 3 is next impressed on the grid of tube -5 by Way ofthetransformer 79.

bridged 7 regeneratively"stabilize or Tube is an amplifier. The radiofrequency output of tube 5 has no practical effect on the 57 and battery13. The radio frequency signal in coil 53 is inductively received bycoil 5'? and fed to the grid of tube 1. Attube l the signal is detectedand an audio frequency output is obtained from tube 1. This audiofrequency outputis fed back into the said amplifying circuit by way ofthe closed-core transformer 65. This said audio frequency output thenobviously is amplified in the alreadydescribed circuit by passingthrough tube 3, transformer 67 tube 5, transformer 69, tube 7 and intothe soundlng device T where the signal may be heard as audio frequency.

The coil 55 is a reaction coil and is adapted to regenerativelystabilize or resonate the detector circuit.

It will be noted that this is substantially a reflexing regenerativecircuit with the tube 1 acting as the detector. However the introductionof the transformer 81 between the amplifying detector circuit preventsshort circuits of high voltage amplifying. circuit batteries from doingdamage in the detector circuit.

The audibility and range is enhanced at low cost as the same amplifyingcircuit handles both audio and radio frequency signals.

In installing the apparatus, and in any required subsequent adjustments,the operator selects the particular tap 19 that is best suited to theother conditions of the circuit.

The extent of cooperation between the fixed and movable coils of eachset 13, 15, and there fore the intensity of current induced by saidcoils is varied by moving the knob 47 rectilinearly in the slot 49whereas rotation of the same knob serves to tune the apparatus to thedesired wave length.

After the operator has rotated and shifted the two knobs 47 to produce asuitable intensity of sound in the translating device T, he adjusts thevariable resistance 77 until distortion of the sound waves produced bythe translating device T isreduced or eliminated.

In the subsequent operation of the apparatus, further adjustment of theresistance 77 may be required in order to improve the results obtainedin listening to diiferent stations, but further adjustment of the tapsl9 is'ordinarily not required.

The number of tubes may be Varied, in order to secure stages ofamplification other than the one herein shown by way of illustration.When some other number of tubes is employed than four, then the circuitsneed to be appropriately altered.

In View of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructionswithout departing from the scope of the invention, it is intended thatall matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

I claim:

1. In a radio system, a dual tuning control comprising a rotary variablecondenser, a stationary inductance, a hinged inductance in variableinductive relation with said stationary inductance, a vertical panel onwhich said condenser is mounted, vertical guides on said panel whichpermit the condenser to be integrally moved therein, a cord secured tothe frame of said condenser and to the hinged inductance, a springaffixed between and to said inductances said spring pulling saidinductances together as the condenser is moved upwardly and tending tocounterbalance the weight of the condenser as said condenser is moveddownwardly, the varying of thecapacity. of said condenser beingcontrolled independently of its vertical movement.

2. In a radio system, a dual tuning control comprising a rotary variablecondenser, a stationary secondary inductance, said condenser shuntingsaid inductance, a hinged plate inductance in variable inductiverelation with said secondary inductance, a vertical panel on which saidcondenser is mounted, vertical guides on said panel which permit thecondenser to be integrally moved therein, a cord secured to the frame ofsaid condenser and to the hinged inductance, a spring tIfiXGCl betweenand to said inductances, said spring pulling said inductances togetheras the condenser is moved upwardly and tending to counterbalance theweight of the condenser as said condenser is moved downwardly, thevarying of the capacity of said condenser being controlled independentlyof its vertical movement.

In testimony whereof, I have signed my name tothis specification this20th day of March, 1924.

LLOYD Q. SLOCUMB.

